1. Field of the Invention
The present invention relates generally to inertia type seat belt retractors and more particularly to an improved support for the inertia sensitive actuating system for such retractors.
2. Description of the Related Art
Locking retractors for safety belts having inertia weight actuators are responsive to acceleration forces applied to the retractor by the vehicle in which the retractor is mounted. In particular, the actuating system is sensitive to forces acting on a frame affixed to the vehicle so that the retractor receives the same acceleration forces as the vehicle. The inertia actuating system typically moves a locking bar or pawl member between a detenting position blocking an unwinding rotation of the safety belt reel and a release position permitting rotation of the reel. The safety belt is wound about a reel that is mounted on a shaft which is secured to the sidewalls of the retractor frame. The pawl is pivotally supported on the retractor frame sidewalls.
One type of inertia sensitive actuating system includes a pendulum supported by a mounting plate having end portions affixed to the retractor frame. The mountings of the reel shaft, the pawl pivot axis, and the pendulum support plate must be closely controlled so as to provide a consistent dimensional relationship therebetween, assuring a dependable and consistent functioning of the inertia lock of the retractor when a vehicle is subjected to acceleration or deceleration forces.
Heretofore, the support plate for the pendulum weight has been molded as a separate part, apart from the retractor frame, in the manner disclosed in reissue U.S. Pat. No. 29,688, reissued July 4, 1978. The pendulum support plate disclosed in that patent comprises part of a stirrup-shaped or U-shaped subassembly comprising three walls, the middle one of which supports the pendulum plate. Alternatively, commonly assigned U.S. Pat. No. 4,166,592 issued Sep. 4, 1979, describes a pendulum support plate having slotted ends received in apertures in the retractor frame sidewalls.
With the above arrangements, the desired dimensional relationship between the reel shaft, the pawl pivot axis and the pendulum support plate may vary somewhat, and such variance is typically detected at a quality control station during assembly of the retractor. It is known, for example, to provide at such station, a clip-like shim or adjusting device on the pawl, by which the relative positioning of the pawl and pendulum support plate may be adjusted to achieve the desired dimensional relationship.
As those familiar with the art will appreciate, seat belt retractors are supplied to the automobile industry in relative large quantities, ad are therefore most economically manufactured using mass production techniques. Given the relative large economy of scale involved, even relatively small savings per unit can result in significant savings to a retractor manufacturer, throughout the production run of a seat belt retractor. As mentioned above, separate support plates have been provided for mounting the inertia pendulum weight. In general, it is desirable to reduce the number of components required for a retractor assembly so as to achieve a savings in inventory costs, and to reduce scheduling problems with a separate manufacturing department or outside vendor for the support plate. Further, assembly of the pendulum support plate as a separate part requires additional labor, typically performed at a work station located on the retractor assembly line.